1. Field of the Invention
The present invention relates to an activity meter that measures an amount of physical activity of a user, and more particularly to an activity meter that converts the amount of physical activity to an activity age and outputs the activity age.
2. Description of the Related Art
For activity meters, JP 2006-204446A and JP 2001-258870A show methods for measuring the exercise intensity of physical activity or the calories burned during physical activity utilizing an acceleration sensor. With the activity meter of JP 2006-204446A, a standard deviation Sw of acceleration in a fixed time period tw is computed from the output signal of the acceleration sensor, and an exercise intensity wi is computed from the standard deviation Sw using a conversion equation formulated in advance. Also, with the device of JP 2001-258870A, the impulse of momentum is calculated by vector synthesis from tri-axial acceleration, and energy expenditure is calculated from the impulse in response to the type of exercise. The type of exercise is determined based on the ratio between the impulse calculated by vector synthesis and the impulse in the depth, horizontal and vertical directions.
In JP 2010-17525A, the age activity pattern that the user's state of activity is equivalent to is computed by comparing the energy expenditure history with reference data.
Although the activity meters of JP 2006-204446A and JP 2001-258870A output the user's activity amount as calories burned, it is unclear whether the amount of calories burned is high or low in comparison with a person of the same age or to a person of what age that amount of calories burned is equivalent.
Although the age activity pattern to which the user's state of activity is equivalent is computed in JP 2010-17525A, the amount of calories burned differs with age even for the same state of activity, and thus it is not appropriate to simply compare calories burned with a person of the same age like in JP 2010-17525A.